'Ortho' is short for Orthochromatic - these films are desensitised to the red part of the visible spectrum which means (a) landscapes look wonderfully dramatic and (b) they can be handled under red safelight without fogging or over-exposure!
Ilford Ortho Plus 80 - 35mm Film
Ilford Ortho Plus 80 - 120 Film
Rollei Ortho 25 - 120 Film
Rollei Ortho 25 - 35mm Film